Guidewires are commonly used in many medical procedures to assist a physician in gaining access to blood vessels within the body to insert instruments. For example, medical procedures involving accessing blood vessels in and around the heart often include making an incision in the femoral artery in the area of the groin or upper thigh, and inserting a medical guidewire into the femoral artery. A physician then manipulates the guidewire while observing it under fluoroscopy or by other imaging techniques to guide the guidewire to a desired location, for example, within the blood vessels in and around the heart.
Guidewires are available in a variety of sizes and configurations. For example, guidewires sizes include but are not limited to diameters of 0.014 inches and 0.035 inches. Guidewires are also available with a variety of tips in a variety of shapes and stiffnesses to accommodate the needs of physicians and to facilitate their manipulation of the guidewires through blood vessels.
Stylets and catheters are also used to access blood vessels in the human body to facilitate the introduction of intravascular leads, stents and other intravascular devices into the veins or arteries of the body. Although both stylets and guidewires are often thought of as simply very small wires, the purpose and operation of guidewires is significantly different as compared to stylets.
Intravascular procedures typically involve an initial step of introducing and routing a guidewire through a patient's vascular system to provide a rail or track along which additional intravascular devices may be introduced. Once a guidewire is in place, an introducer sheath catheter is routed over at least a portion of the guidewire to provide a larger opening into the vein or artery and sometimes to protect the inside walls of the vessels along the route of the guidewire. With the introducer in place, the guidewire may be removed or may remain in place as additional intravascular devices, such as intravascular leads, stents and catheters are introduced into the patient's vascular system.
To better accomplish the purpose of a guidewire providing a track along the patient's vascular system for other intravascular devices, it is desirable that the guidewire be extremely flexible and preferably have the ability to vary the flexibility of the distal tip and/or deflect the distal tip so as to aid in routing the guidewire through the patient's vascular system.
In contrast to the guidewire that serves as a track over which other intravascular devices are routed, a stylet is used within an internal lumen of an intravascular device both to push that device through the vascular system and to steer the device as it is being pushed. Although some intravascular devices are designed to steer themselves using internal core wires, almost all leads and some catheters have an inner channel or lumen into which a stylet may be inserted.
In addition to pushing the intravascular device through the vascular system by engaging the distal end of the device, the stylet also serves to deflect the distal end of the intravascular device so as to steer the distal end through the vascular system. Unlike the lead, catheter or guidewire, which is highly flexible and floppy, the stylet must be stiffer and more rigid so as to enable the stylet to push the lead or catheter through the patient's vascular system.
Conventionally, stylets having different bends on the distal end are used at different points of advancing the lead or catheter to a desired location. For straight segments of a vessel a straight stylet is used, whereas a stylet with a curved distal tip is used to navigate the lead or catheter through a curved portion of a vessel.
It is often necessary to change guidewire size during medical procedures. Currently, changing guidewire size involves withdrawing a guidewire that is currently located in the blood vessel and inserting a different size guidewire into the blood vessel and guiding it to the position previously occupied by the original guidewire. This can be a time consuming procedure, which lengthens the time necessary to a complete a medical vascular procedure and may increase discomfort and risk for the patient. In general, it is desirable to complete invasive medical procedures such as medical vascular procedures as quickly and efficient as possible to minimize stress on the patient.
Thus, there is room for improvement in the guidewire arts to improve efficiency and minimize time required to complete vascular medical procedures.